الفهرس 
Materials collectionOnly 14 pages are availabe for public view
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Abstract
The following study is the first of its kind to El-Farafra
Oasis. It includes a detailed monography on species
composition and algal assemblages of different air, water and
soil habitats during two successive seasons: summer 2011 and
winter 2012. The work contains a taxonomic list of 101
different algal taxa related to 56 genera: Cyanophycophyta (64
taxa), Bacillariophycophyta (3 taxa), Xanthophycophyta (7
taxa), Euglenophycophyta (4 taxa), Chlorophycophyta (22
taxa) and charophycophyta (one species). Of these, 10 species
were recorded for the first time in the Egyptian air, freshwater
and soil algal flora: Westiellopsis prolifica, Cylindrospermum
gregarium, C. licheniforme, Symploca dubia, Chlorocloster
caudatus, Tetraktis aktinastroides, Penium margaritaceum,
Cosmarium blyttii, Zygnemopsis sp. and Nitellopsis obtusa.
This study isolated only five airborne algal taxa during
the summer collection: Myxosarcina chroococcoides,
Westiellopsis prolifica, Oscillatoria acuminata, Lyngbya
limnetica and Schizothrix braunii. Therefore, it can be
concluded that high temperature and dryness characterizing the
summer season in El-Farafra Oasis resulted in flaking up of
dried airborne algal propagules from the soil surface and other
ecosystems into the air. In addition, Cyanophycophyta tend be
the widely-dispersed division as airborne algae.
Springs and their counterpart habitats “wells” inhabiting
El-Farafra Oasis are considered to be relatively isolated
ecosystems from the physico-chemical and phycological
standpoints. Ain El-Balad could be classified as the only
“slightly hot” spring, whereas Ain El-Hateyya, Ain Bishwa
and Ain Goshna commonly follow the ambient-to-thermal
gradients. The drilled wells have thermal-to-hot gradients. All
springs, except Ain Goshna, and wells could be assorted as
typically freshwater habitats with almost circumneutral to
slightly alkaline pH. Ca/Na-chloride salts constituted the
dominant water salts in El-Farafra Oasis, with some noticeable
contributions by Mg/Ca-bicarbonates and sulphates.
The studied groundwater habitats (springs and birs) in ElFarafra Oasis are considered suitable, to a large extent, for
human drinking and all other domestic purposes in the context
of the maximum-permissible water quality guidelines
proposed by the Egyptian Higher Committee for Water
“EHCW” and the World Health organization “WHO”.
However, they still essentially need a special governmental
attention to eliminate /or reduce the relatively higher
concentrations of trace elements specifically Fe and Mn.
Furthermore, groundwater of El-Farafra Oasis is considered an
excellent-to-good resource for irrigation based on the
conductivity gradients and Cl
concentrations.
76 different algal taxa had been identified from all water
habitats including the naturally-propagated and culturing
materials. For more details, 64 species were recorded from the
natural collected materials and belonged to: Cyanophycophyta
(38 taxa), Bacillariophycophyta (3 taxa), Xanthophycophyta (2
taxa), Euglenophycophyta (4 taxa), Chlorophycophyta (16
taxa) and charophycophyta (one taxon). For the culturing
waters, 27 species had been revealed, and out of them new 12
species appeared using the different culturing techniques Cyanophycophyta (19 taxa), Chlorophycophyta (6 taxa) and
Xanthophycophyta (2 taxa). Representatives of family
Oscillatoriaceae constituted qualitatively the highest number in
all studied sites. In particular, Oscillatoria tenuis, followed by
O. subtilissima, O. jasorvensis and O. okenii were the most
widespread taxa in natural waters. Most of the identified algal
taxa inhabiting the springs and their artificial habitats “wells”
perfectly fit with their ecological preferences, e.g.: Gloeothece
samoensis var. major, Westiellopsis prolifica, Scytonema
ocellatum, Calothrix elenkinii, Oscillatoria acuminata, O.
animalis, O. carboniciphila, O. deflexa, O. jasorvensis, O.
okenii, O. redekei, O. sancta, O. splendida, O. subtilissima, O.
terebriformis, Phormidium corium, Symploca dubia and
Zygnemopsis sp. Nevertheless, there are many other algal taxa
that showed a strong affinity to the other studied ecosystems
(lakes, agricultural drainage and ditch). For instance,
Merismopedia tenuissima, Pseudoholopedia convoluta,
Microcystis aeruginosa, Coelosphaerium kuetzingianum,
Euglena acus, E. oxyuris, E. texta, Lepociclis fusiformis,
Penium margaritaceum, Closterium acerosum, Micrasterias
truncata, Cosmarium blyttii, C. laeve, C. pachydermum,
Spirogyra reinhardii and the charophyte alga Nitellopsis
obtusa.
Some of the identified algal taxa are considered as
excellent bio-indicators for eutrophication in El-Farafra Oasis.
Among them, the widely-distributed, non-heterocytous bluegreen algae Oscillatoria limosa, O. princeps and O. tenuis
mightily linked to the relatively-high availability of nitrates
and orthophosphates. In general, the algal flora of different
habitats in El-Farafra Oasis is composed of some oligosaprobous forms, e.g. Vaucheria geminata and V. sessilis,
with the presence of some β- mesosaprobic tolerants such as
Oscillatoria limosa, O. princeps, Euglena acus and
Coelastrum cambricum var. intermedium. Little contributions
of α-mesosaprobic taxa, e.g. Oscillatoria tenuis and Euglena
oxyuris and the rarely polysaprobic taxon Anabaena constricta
were also detected.
The Canonical Correspondence Analysis (CCA) pointed
out that there is a strong positive relationship between
Cyanophycophyta and the water temperature. But this algal
group is inversely correlated with NO2
-N, NO3
-N and S.R.P.
Euglenoids usually prefer inorganic and organic polluted
habitats rich in nitrates and nitrites such as lakes and
agricultural drainages. Green algae usually proliferate in
alkaline pH environments. The only representative member of
Charophytes Nitellopsis obtusa was found in an alkaline
agricultural ditch with moderately-hard water during the
winter collection.
Regarding to the soil algal composition,
Cyanophycophyta contributed the dominant division with 33
different species belonging to 18 genera and most of them are
related to orders Nostocales and Oscillatoriales. Other
identified taxa were belonged to Chlorophycophyta (5
species), Xanthophycophyta (5 species) and diatoms (3
species). The dominance of blue-green algae in the desert soil
of El-Farafra Oasis is compatible with its alkaline nature.
However, there is no absolute relationship between each algal
division and the determined physico-chemical parameters.Finally, this study highly recommends using of the
isolated blue-green algal taxa of El-Farafra Oasis, specifically
Scytonema ocellatum and Westiellopsis prolifica due to their
highest potentials on atmospheric nitrogen fixation, as
ecofriendly environmental natural biofertilizers for the
sustainable development promised in this desert habitat.